Lamp support arm



FIG. 1 is a perspective view from above of a lamp support arm inaccordance with my design;

FIG. 2 is a perspective view from below of a lamp support arm inaccordance with my design;

FIG. 3 is a side elevation view of the lamp support arm in accordancewith my design; and,

FIG. 4 is a top plan view of the lamp support arm in accordance with mydesign.

The broken lines showing environmental structure are for illustrativepurposes and form no part of the claimed design.

The ornamental design for a lamp support arm, as shown and described.